DM: eth: Switch display5 board to use DM_ETH

After this commit the display5 device would use FEC driver supporting
driver model (DM_ETH).

Signed-off-by: Lukasz Majewski <lukma@denx.de>
diff --git a/arch/arm/mach-imx/mx6/Kconfig b/arch/arm/mach-imx/mx6/Kconfig
index 7ccebc3..032fd56 100644
--- a/arch/arm/mach-imx/mx6/Kconfig
+++ b/arch/arm/mach-imx/mx6/Kconfig
@@ -197,6 +197,7 @@
 config TARGET_DISPLAY5
 	bool "LWN DISPLAY5 board"
 	select DM
+	select DM_ETH
 	select DM_I2C
 	select DM_MMC
 	select DM_GPIO